Cant be trusted

Bought a basketful of aviation calculators for fun. Ran a few tests and the myE6B AirNav came up short in the first few minutes of reviewing.
Problem: From Conversions > Speeds> enter 660 knots and note the Mach number. Says: "0.10 Mach" Thats odd. A math bug? More problematic--because it would be a conceptual problem rather than just a bug--is that a mach calculation would be provided without an OAT input.
Sorry to say, but if I find a problem this quick, I cant trust it in the air. Im deleting this app.

mzeet about E6B Aviation Calculator